Materials applicable for dental impression are well known in the art.
Commonly used classes of dental impression materials are typically based either on addition- or condensation crosslinking-reactions of polyorganosiloxane containing components as described e.g. in U.S. Pat. No. 5,064,891, EP 0 729 341 A1 or U.S. Pat. No. 4,657,959 or on polyether technology, e.g. azridino-polyethers as described e.g. in EP 1 210 055 B1.
Recently, also hybride materials of polyorganosiloxanes and polyether as described e.g. in EP 1 290 998 A1 are available. The mentioned materials typically possess a variety of properties including a fast setting behaviour and a good dimensional stability. Generally, the materials are provided in two components to be mixed prior to use and cure by a crosslinking-reaction.
An important aspect for dental impression material, especially for polysiloxane based materials (VPS materials), is to make those by nature hydrophobic materials hydrophilic. Means to accomplish this task can be found in EP 1 893 163 A1, EP 2 165 693 A2, EP 0 244 478 B1, EP 0 231 420 B1 or EP 0 613 926 B1. Recently, even improved systems for the hydrophilization of VPS materials have been described, e.g. in EP 1 976 479 B1, EP 2 386 287 A2 or EP 2 231 102 B1.
One problem associated with the higher hydrophilization of silicone impression materials, however, is the storage stability of the obtained pastes, i.e. base paste and catalyst paste.
Therefore, the use of scavengers for the absorption of water such as CaSO4 or CaCl2 as well as Zeolithe A for the stabilization of the base paste have been described in WO 98/53791 A2.
Another approach to stabilize dental impression material is described e.g. in EP 1 893 163 B1 or WO 2007/001869 A2. There, phosphorous based compounds are used for the stabilization of the base paste of hydrophilized addition-curing silicone formulations. U.S. Pat. No. 5,367,001 (Itho et al.) describes an impression composition comprising a polyether polymer having at least two alkenyl groups in the molecule, a polyorganohydrogensiloxane having at least three silicon-bonded hydrogen atoms in its molecule, a platinum catalyst, an inorganic filler and an antioxidant. As suitable fillers fine powdery silica, quartz powder, glass fiber, carbon powder, iron oxide, titanium oxide, zinc oxide, calcium carbonate and magnesium carbonate are described.
WO 99/27895 (Curtis et al.) describes a dental impression composition containing a color change indicator. The impression composition is based on a thermoplastic material like polycaprolactone and may contain filler, an antioxidant and a stabilizer.
US 2007/0173557 A1 (Bublewitz et al.) describes a condensation cross-linked dental material base on alkoxysilyl-functional polyethers. The dental material may contain stabilizers and/or antioxidants.
As nowadays systems with increased hydrophilicity are available, there is a need for improved dental impression materials having e.g. a long shelf-life.